A very smart, very awesome girl named Kellbot who has a love for Katamari has made a prototype for what I consider to be the the ultimate Katamari controller. I really hope Namco sees this video and this controller is made in a retail market (dare to dream).
The controller is a giant metalic sphere that controlls the in game ball exactly the way you move it. It's able to do this via an optical mouse that tracks the balls motion. Kellbot then got her hands on some used PS2 controllers, ripped out the potentiometers on the analog sticks, and replaced them with a digital potentiometer and an arduino. The arduino takes signals from a PS/2 mouse and adjusts the potentiometer accordingly.
If none of that above made sense, you're probably not alone and all you need to do is watch the video below. However, if you have a knack for this kind of thing and want to know more about this awesome project or Kellbot you can check out the original post from her blog here.
[Thanks to Casey White for this find!]